CONSERVATION OF MOISTURE. 



45 



Mulching. Evaporation from the surface of the soil may be 

 largely prevented by the use of mulch, and to some extent by the 

 cultivation of the surface of the land. The use of a mulch is quite 

 generally accepted as being desirable around trees, shrubs and 

 small-fruit plants, but its exact value is seldom expressed in fig- 

 ures. At the Experiment Station, the past season, the value of a 

 mulch was clearly shown in many cases. In one case a strawberry 

 bed growing on open clayey loam which was heavily inulched with 

 oat straw produced a tine crop of strawberries, while strawberry 

 beds in the immediate vicinity, not so treated, were nearly or quite 

 a failure. In fact, this crop was generally a failure in eastern Min- 

 nesota the past season, with rare exceptions. The success at the 

 Experiment Station could not be ascribed to the use of any particu- 

 lar variety, since all the well known kinds were productive. It would 

 seem to be partially due to high cultivation, but chiefly to the use of 

 a heavy mulch between the rows, which had become very compact 

 from being under the snows all winter. Some analyses made by 

 Prof. Snyder, the station chemist, showed the results set forth in the 

 following table, in which the term "mulched bed" is ixsed to signify 

 the rows of the strawberries which at the time of trial were covered 

 with about three inches of broken compacted oat straw; ''cultivated 

 soil" means the land in an adjoining row which -was kept stirred by a 

 horse cultivator;- "uncultivated soil" refers to parts of the strawberry 

 beds where the plants had failed and, consequently, no cultivation 

 whatever was given the land, neither was it mulched. The data un- 

 der the heads of cultivated and uncultivated land were probably 

 much influenced by the proximity of the tnulched rows, which, un- 

 doubtedl}^, greatly increased the amount of water which they con- 

 tained; so the results in the table are much modified by it and do 

 not appear as evident as they would otherwise. Great care was 

 taken in selecting the samples to have them from soils of similar 

 appearance, and the soil of the whole bed was very uniform. 



From this table, it appears that the use of a mulch on the surface 

 soil increased the amount of water it held about five per cent, as com- 

 pared with soil which was cultivated. Calling the weight of a cubic 

 foot of dry soil seventy pounds, which is approximately correct, it 

 will be seen that the use of a mulch resulted in making each cubic 

 foot of the surface soil retain about three and one-half pints of water 

 more than it otherwise would. This is equivalent to increasing the 

 amount of water in the upper one foot of soil of one acre by 605 bar. 

 rels. Of course, these figures are only approximate and there are 

 many possible sources of error, yet it would seem that enough was 

 shown to demonstrate that the use of a mulch might easily make the 

 diflference between success and failure in maturing a crop of this 

 nature. 



Physicists estimate that in order to be in the best condition for 

 the roots of the cultivated plants to act, the soil should contain 



